Saturday 7 July 2012 19.05 EDT
First published on Saturday 7 July 2012 19.05 EDT

So you find me, a decade after I first put pen to paper in service of my countrymen and women, that most elusive of human specimens: an emotionally flawless human being. As the Observer Magazine's reigning agony queen for the past 10 years, I have dispensed my advice from halcyon moral heights. I have gazed, weekly, from my eyrie at the conscience-wrestling antics of my merely mortal readers.

Only this morning, as I told my husband I was way too busy for sex, screamed at my nanny for not finishing my children's homework and chucked the dog in the bath to pee so I wouldn't have to walk her before checking how many new Twitter followers I've gained overnight, I thought: "Well done, Mariella – you've really got things sorted!"

Translating any insights I have for strangers' lives into positive action in my own has proved a challenge. While I've learned a lot about what everyone else is thinking, I fail miserably to use such knowledge in my private relationships. As my husband will readily attest, if he can grab my attention from my BlackBerry during dinner, or as my children will whisper between my hollers of frustration, I'm prone to wander as far from emotionally functional as a human being can without requiring residential care.

Luckily for me I've landed one of the few jobs where past crimes and current misdemeanours enhance your qualifications. Self-pity is the only vice I don't indulge in – and that's directly the result of my mailbag. As I've pointed out throughout my tenure, there's nothing like a mailbag full of other people's problems to put your own in perspective. Worrying about whether you can afford to take the kids somewhere sunny for the holidays? A letter from a father of four who's about to lose his in a divorce battle quickly sets your priorities straight. Feeling murderous towards your best friend for being flaky? A missive from a woman who's discovered hers has been sleeping with her husband for 10 years obliterates your own friend's trifling transgressions.

There are few dilemmas I haven't had contact with at some point, though I have to admit I have been flummoxed on occasion. There was the father of two who wrote to me from India, complaining about his bullying wife, asking whether I felt her sister in the UK might be a better choice for him… and whether her lack of response to his love letters could be considered a come-on. Or the heterosexual husband who had a drunken snog with his neighbour on the way home from the pub and wondered if he should embrace a life of cruising gay clubs as a result of this one transgression. Proof that passion can often be the enemy of common sense.

Sure, it's easy to be blinded by desire, but even once those ardent emotions have levelled out we seem to struggle more than we should. Despite statistics that give long-term unions no more than a 50% chance of survival we separate acrimoniously, selfishly and with a conspicuous absence of rationality. It's clear from my postbag that we waste ridiculous amounts of time, energy and money in divorce courts when we should be turning to mediation.

On some occasions, though, it's hard to see a path back from selfish behaviour. I was particularly animated by a letter from a mother of seven whose husband, on the day she returned from hospital with the youngest child, "walked out to buy film and never returned" but now wants full access to his children – despite her having raised and supported them as a single parent for a decade. Other letters are more amusing, such as the gentleman surprised that his admission to his wife that he liked wearing ladies' lingerie had "cooled our relationship like a trip to the Antarctic".

As I look back on 10 years of agony, I still feel like a novice, and each week I'm humbled, moved and slightly amazed at the responsibility readers give me. Whether it's a rape that's never been confessed to, embarrassment at virginity in adulthood, self-indulgent children that parents despair of, desire to have a baby, fears for a sibling, dismay at betrayal or disappointment with life… my postbag is a constant source of wonder and consternation, full of stories that, if you found them in fiction, would test your credulity and heartstrings to the maximum. It's also still full of surprises.

The most striking element about the cacophony of human woe I receive is how timeless the contents are. We think we're ubermodern here in the 21st century, and on the surface we do live radically altered lives from those of our ancestors, with technology allowing us to keep constant tabs on those around us and beyond. Yet the majority of letters I get are about loneliness. If you asked me what emotional ailment was at epidemic levels, I'd say alienation and an unfulfilled yearning to truly connect with fellow beings, whether it's friends, family, lovers or long-term partners.

So much for the church of the chat room. Once you've said goodnight to your 200 Twitter followers the world can become a silent and intimidating place. With the internet we can communicate instantly across the globe, but the net also makes it possible for us to shrink ever further into our own skins – a state of being that neither suits the human temperament nor provides ground for further growth. We are social animals, but online our desire to be heard is often answered only by echoes of the one-dimensional communications we send out.

As for tweeting and texting: impassioned discussions, particularly when they're intimate, don't work in abbreviated script messages. No relationship should begin or end in 140 characters. Neither has any grievance ever been smoothed over at the midnight hour, with drink taken and a live communication device in your hand. A tweet in similar circumstances can become a weapon of mass destruction. A breathalyser on all networking devices would get my vote, and a blanket ban on them at mealtimes (as I said to my family while writing this on my laptop during dinner).

Which brings me to sex. It's clearly a wild, crazy world out there. The good news is, judging by my correspondents, there's someone for everyone. Along with the endless letters from partners not getting enough – and I do wish my husband would stop cluttering up my inbox on that matter – there are a myriad of variations on the sexual theme.

Take, for instance, the aspiring beekeeper who found that studying this prospective hobby was far more enticing than sex with his wife. Just imagine the impact on his relationship if he'd actually taken it up rather than just researched it! Another reader was so traumatised by his partner's profile – her nose reminded him of an aunt who'd terrified him as a child with tales of a haystack monster – that every time he glimpsed her from the wrong angle he was turned off. Nostalgia is on the rise, in particular the number of people reflecting on, or regretting that they didn't pursue, early loves. This tendency to covet what we haven't got, or rue what we had but lost, is reserved only for our species: imagine monkeys shaking their heads at memories of bananas peeled but left uneaten and you'll sense how silly such regrets are. Relationships in the past are memories to immerse yourself in when the world isn't going your way, but certainly not where future dreams should be focused.

Finally, a reminder of how our lives pivot on the smallest twists of fate came from a 22-year-old "normal heterosexual", as he described himself, who let his best friend dress him as a girl for a fancy-dress party. His female persona proved irresistible to a King Kong and, far from being horrified by pursuit by a 6ft primate, he found himself strangely attracted and began a flirtation with the ageing sugar daddy under the mask. He wanted my opinion on whether he should take things into the bedroom, having never contemplated same-sex sex in his life but, he said: "I don't want to wake up screaming in a luxury apartment in the middle of the night, even on Armani bed linen." My conclusion was that once you're checking the quality of the sheets, your mind is already made up.

Nathanael West's wonderful early 20th-century novel Miss Lonelyhearts describes a newspaper agony columnist so demoralised by exposure to mankind's misery that his own life begins to unravel. Unlike the case of Miss Lonelyhearts, my postbag has had the opposite impact. I'm constantly struck by our capacity for love and forgiveness, our need to engage and communicate with each other, and just how decent and well-meaning the majority of human beings are.

Not that such characters get much airtime in our trauma-addicted world. Quite honestly, if we do manage to destroy the planet with our devil-may-care attitude to natural resources I'd suggest we leave, as a dossier in our defence, the collected letters to agony aunts and uncles down the generations. It would certainly prove that we weren't all bad!